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Analysis of Metric Spaces
Rating: 5.0 out of 5(2 ratings)
46 students

Analysis of Metric Spaces

The world according to Rudin
Created byDan Kucerovsky
Last updated 5/2023
English
English [Auto],

What you'll learn

  • Effectively locate and use the information needed to prove theorems and establish mathematical results.
  • Effectively write mathematical solutions in a clear and concise manner.
  • Demonstrate an intuitive understanding of set theory and metric spaces
  • Understand the classic book Principles of Mathematical Analysis by Rudin

Course content

1 section24 lectures28h 32m total length
  • Introduction and Chapter 2 of Rudin1:23:13

    Explore infinity as a process and infinite sets (chapter two), define finite sets, and introduce set equivalence via bijections, setting the stage for topological and metric spaces.

  • Basic Set Theory57:53

    Examine how infinite sets relate to proper subsets via 1-to-1 and onto functions. Compare finite, countable, and uncountable sets using sequences.

  • Sequences1:07:56

    Analyze sequences and subsequences, define countable sets and unions and intersections, explore De Morgan's laws, and illustrate Cantor's theorem with the countability of rational numbers and multiple proofs.

  • Real and Rational Numbers1:04:58

    Analyze the relationship between real and rational numbers, understand the completeness property, and learn how decimal expansions distinguish rationals from irrationals via repeating and terminating decimals.

  • The real numbers are uncountable1:09:21

    Explore why the real numbers are uncountable, using decimal expansions, repeating decimals, and Cantor's diagonal argument, with connections to fractions and set theory.

  • Russel's paradox: not _everything_ can be a set1:58:06

    Explore Cantor's diagonal argument proving real numbers are uncountable, inspect finite, countable, and uncountable sets, and introduce Cartesian products, equivalence relations, and invertible mappings in set theory.

  • More on Paradox... and the start of Metric Spaces1:08:32

    Examine the paradox of the set of all sets, then introduce metric spaces defined by a distance function, including open neighborhoods and limit points.

  • Neighbourhoods in Metric space55:06

    Explore neighborhoods in metric spaces by defining radius-based balls, and identify limit points, interior points, and isolated points, while comparing open and closed sets in Euclidean space.

  • Interior Points, Open, Closed, and Clopen51:22

    Explore interior points, open and closed sets, and limit points in metric spaces through neighborhoods, boundaries, and set complements.

  • Dense Sets and Perfect sets52:20

    Explore dense sets and perfect sets in metric spaces, using limit points and neighborhoods to contrast closed, discrete, and rationals in R.

  • Closed, bounded, compact56:05

    Analyze closed, bounded, and compact sets within metric spaces, clarifying how these properties interact and framing compactness in the context of metric space analysis.

  • Open is not the opposite of closed1:11:57

    Examine how open and closed sets relate in metric spaces, proving open iff complement is closed, via interior points, limit points, and De Morgan's laws.

  • Not limits, but Limit Points. Closures.1:10:45

    Explore the closure operation in metric spaces, linking closedness and limit points, and contrast open and closed sets through unions, intersections, and the role of compactness as analogy to boundedness.

  • Compactness: a very clever generalization of closed intervals of the number line1:07:47

    Explore how compactness generalizes closed intervals in metric spaces via open covers and finite subcovers. Realize that compact sets are closed and finite point sets are compact.

  • More on compactness59:27

    Examine compactness in metric spaces, showing compact sets are closed, and that in Euclidean space closed and bounded subsets are compact. Show continuous images of compact sets remain compact.

  • Review47:20

    Explore compactness through finite unions of compact sets, intersections (or empty), and open covers with finite subcovers, and discuss cartesian products, product versus box topology, Tychonoff's theorem, and perfect sets.

  • Properties of compact sets and of perfect sets1:00:24

    Explore the properties of compact and perfect sets in metric spaces, focusing on limit points, interior, closure, and the finite intersection property, including the uncountability of perfect sets.

  • The real line: Sequences and Series54:50

    Explore the real line through sequences and series, covering divergence and comparison tests, the geometric series, and Cauchy condensation, with a focus on convergence via bounded partial sums.

  • The Cantor set: Is it connected?58:04

    Explore compactness and open covers in metric spaces, apply De Morgan's laws, and construct the Cantor set in [0,1], illustrating measure zero and uncountability.

  • Sequences in Metric Spaces49:31

    Examine connectedness in metric spaces via partitions into open and closed components and limit points, then introduce convergence of sequences in metric spaces using epsilon–N definitions.

  • More on sequences in Metric Spaces1:04:31

    Explore convergence and limit points of sequences in metric spaces using epsilon-neighborhood criteria, with complex-number examples, divergence cases, and the distinction between limits and limit points.

  • Another clever generalization: completeness through Cauchy sequences1:19:22

    An exploration of completeness in metric spaces through Cauchy sequences, including the relation to compactness and completion, with examples from countable spaces, limit points, and subsequences.

  • Comparing the two kinds of completeness4:00:00

    Explore the Cauchy criterion for convergence in sequences and metric spaces, and compare it with monotone completeness, series, and standard tests such as divergence and comparison.

  • Continuity: a property of maps of metric spaces43:55

    Examine two equivalent definitions of continuity between metric spaces: preimage of open sets and epsilon-delta conditions. Discuss implications for isometries, composition, and power series with root tests.

Requirements

  • Mathematical maturity. In other words, be interested in mathematics.

Description

The methods of calculus are limited to Euclidean spaces. In this course, we show how the incredibly powerful tools of calculus, beginning with the limit concept, can be generalized to so-called metric spaces. Almost every space used in advanced analysis is in fact a metric space, and limits in metric spaces are a universal language for advanced analysis. The basic techniques of calculus were invented for the real line R. What should we do when we want to handle something more general than R? The fundamental notions of calculus begin with the idea that one point of R can be close to another point of R, and this is called "Approximation" or "taking a limit." Metrics are a way to transfer this key notion of being "close to" to a more general setting. The "points" of a metric space can be complicated objects in their own right. For example, they may themselves be functions on some other space. Ideas like this are ubiquitous in advanced mathematics today. One tries to throw away complicated details of the space being considered, and this makes it easier to see which theorem or technique can be applied next. In this way, the mathematician tries to avoid getting overwhelmed by the details, or to say it differently, we try to see the overall forest rather than the trees.

Who this course is for:

  • Have you tried to read the classic book Introduction to Mathematical Analysis by Rudin and been stimied? Take this course!